Pranaxis MCP Gateway
Consistency verdicts for MCP tool calls. A transparent stdio proxy that sits between any MCP client (Claude Code, Cursor, Codex, custom agents) and any MCP server. Reads pass through untouched. Calls that consume a shared resource (launch a run, pay an order, write a file at a given sha, update a row) are arbitrated first: if another agent already holds that resource version, the call never reaches the tool and the agent gets a readable error with a certificate.
It solves the lost update of multi-agent systems: two agents, each inside its own policy, consuming the same thing twice.
agent ──stdio──▶ pranaxis-mcp ──stdio──▶ your MCP server ──▶ tool
│
└── verdict (software, or the Pranaxis chip)
Install
pip install pranaxis-mcp-gateway # or: uvx pranaxis-mcp-gateway
Use
Register the gateway in your MCP client instead of the server, with the server as the child command. One gateway per agent,
each with its own --agent-id; all gateways on a machine share the version state. Claude Code example, AMD Ross Vivado server:
claude mcp add vivado-mcp --scope project --transport stdio --env VIVADO_PATH=/path/to/vivado -- \
pranaxis-mcp --agent-id agent-a --rules vivado-ross -- vivado-mcp-server --stdio-bridge
GitHub MCP server:
pranaxis-mcp --agent-id agent-a --rules github-official -- npx -y @modelcontextprotocol/server-github
A denied call returns isError: true with a message like:
DENIED by the Pranaxis consistency verifier.
Resource 'owner/repo/main/README.md' version abc123 is being consumed by another agent
(holder: agent-a; their request: agent-a-3f2c...). Certificate: ...
Your call did NOT reach the tool. Do not retry the same write; read the current state and work from it.
Tool descriptions are annotated so the agent knows writes are arbitrated. In our tests, agents (two different models) did not retry blindly after a denial: they read the state and chose another action.
Rules: what counts as consumption
Rules are data, one JSON file per MCP server (src/pranaxis_gateway/rules/). Each rule names the tool, matches arguments
with regexes (named groups become fields), builds the resource name from a template, and optionally takes the version from
an argument (e.g. GitHub's previous blob sha). release rules say which responses show a resource complete.
A completed resource stays with its holder until the holder makes its next call (it collected the result) or a grace period
expires (--grace, default 600 s): nobody wipes someone else's result before they read it.
Bundled: vivado-ross (AMD Ross Vivado MCP server), github-official, postgres-generic. Calls matching no rule pass
through and are logged as passthrough. Contributions of rules for other servers are welcome.
Verifiers
--verifier stub(default): software reference. Holders shared through the state file; verdicts carry no physical measurement.--verifier fam --fam-endpoint host:port: the Pranaxis physical verifier, a ring-oscillator block on an AMD Zynq UltraScale+ / Kria device that measures the arbitration and returns a certificate with sieve, frequencies, tolerance and timing. The hardware is a separate product (https://pranaxis.eu); this repository contains only the gateway and the HTTP contract it speaks.
Certificates
Every verdict is appended to ross_demo_YYYYMMDD.jsonl (name configurable with --log-file): agent, resource, version, decision,
reason, conflicting request, certificate id, measurement data when physical, proxy latency. Read-only calls are logged as passthrough.
Tests
python tests/test_two_agents.py --verifier stub # two agents, Vivado-like server: P1..P4
python tests/test_rules_generic.py # GitHub and SQL rule files
Status and roadmap
0.3: local mode (one proxy per agent, stdio), declarative rules, holder release / grace, jsonl log. Measured with the physical verifier on a ZUBoard 1CG (10/10 preregistered runs) and with two real agents on AMD Ross. Next: central mode (one network gateway for all agents, audit API), embedded mode on Kria K26.
Intellectual property and licence
Code: Apache-2.0. The arbitration procedure and the physical device are covered by Spanish patent applications P202631184 and P202631345 (Arignatxa S.L. as licensee); using this gateway with the software verifier is free; the physical verifier bitstream is not part of this repository. "Pranaxis" is a trademark application (M4406608).